.TH std::ranges::move,std::ranges::move_result 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::ranges::move,std::ranges::move_result \- std::ranges::move,std::ranges::move_result

.SH Synopsis
   Defined in header <algorithm>
   Call signature
   template< std::input_iterator I, std::sentinel_for<I> S,
   std::weakly_incrementable O >

   requires std::indirectly_movable<I, O>                             \fB(1)\fP \fI(since C++20)\fP
   constexpr move_result<I, O>

       move( I first, S last, O result );
   template< ranges::input_range R, std::weakly_incrementable O >

   requires std::indirectly_movable<ranges::iterator_t<R>, O>         \fB(2)\fP \fI(since C++20)\fP
   constexpr move_result<ranges::borrowed_iterator_t<R>, O>

       move( R&& r, O result );
.SH Helper types
   template< class I, class O >                                       \fB(3)\fP \fI(since C++20)\fP
   using move_result = ranges::in_out_result<I, O>;

   1) Moves the elements in the range, defined by [first, last), to another range
   beginning at result. The behavior is undefined if result is within the range
   [first, last). In such a case, ranges::move_backward may be used instead.
   2) Same as \fB(1)\fP, but uses r as the source range, as if using ranges::begin(r) as
   first, and ranges::end(r) as last.

   The elements in the moved-from range will still contain valid values of the
   appropriate type, but not necessarily the same values as before the move.

   The function-like entities described on this page are niebloids, that is:

     * Explicit template argument lists cannot be specified when calling any of them.
     * None of them are visible to argument-dependent lookup.
     * When any of them are found by normal unqualified lookup as the name to the left
       of the function-call operator, argument-dependent lookup is inhibited.

   In practice, they may be implemented as function objects, or with special compiler
   extensions.

.SH Parameters

   first  - the beginning of the range of elements to move
   last   - the end of the range of elements to move
   r      - the range of the elements to move
   result - the beginning of the destination range

.SH Return value

   {last, result + N}, where

   1) N = ranges::distance(first, last).
   2) N = ranges::distance(r).

.SH Complexity

   Exactly N move assignments.

.SH Notes

   When moving overlapping ranges, ranges::move is appropriate when moving to the left
   (beginning of the destination range is outside the source range) while
   ranges::move_backward is appropriate when moving to the right (end of the
   destination range is outside the source range).

.SH Possible implementation

  struct move_fn
  {
      template<std::input_iterator I, std::sentinel_for<I> S, std::weakly_incrementable O>
      requires std::indirectly_movable<I, O>
      constexpr ranges::move_result<I, O>
          operator()(I first, S last, O result) const
      {
          for (; first != last; ++first, ++result)
              *result = ranges::iter_move(first);
          return {std::move(first), std::move(result)};
      }
      template<ranges::input_range R, std::weakly_incrementable O>
      requires std::indirectly_movable<ranges::iterator_t<R>, O>
      constexpr ranges::move_result<ranges::borrowed_iterator_t<R>, O>
          operator()(R&& r, O result) const
      {
          return (*this)(ranges::begin(r), ranges::end(r), std::move(result));
      }
  };

  inline constexpr move_fn move {};

.SH Example

   The following code moves thread objects (which themselves are non copyable) from one
   container to another.


// Run this code

 #include <algorithm>
 #include <chrono>
 #include <iostream>
 #include <iterator>
 #include <list>
 #include <thread>
 #include <vector>
 using namespace std::literals::chrono_literals;

 void f(std::chrono::milliseconds n)
 {
     std::this_thread::sleep_for(n);
     std::cout << "thread with n=" << n.count() << "ms ended" << std::endl;
 }

 int main()
 {
     std::vector<std::jthread> v;
     v.emplace_back(f, 400ms);
     v.emplace_back(f, 600ms);
     v.emplace_back(f, 800ms);

     std::list<std::jthread> l;

     // std::ranges::copy() would not compile, because std::jthread is non-copyable
     std::ranges::move(v, std::back_inserter(l));
 }

.SH Output:

 thread with n=400ms ended
 thread with n=600ms ended
 thread with n=800ms ended

.SH See also

   ranges::move_backward moves a range of elements to a new location in backwards order
   (C++20)               (niebloid)
   ranges::copy
   ranges::copy_if       copies a range of elements to a new location
   (C++20)               (niebloid)
   (C++20)
   ranges::copy_backward copies a range of elements in backwards order
   (C++20)               (niebloid)
   move                  moves a range of elements to a new location
   \fI(C++11)\fP               \fI(function template)\fP
   move                  obtains an rvalue reference
   \fI(C++11)\fP               \fI(function template)\fP
